Ticks and Tick-Borne Pathogens: And Now What?

Dear Colleagues,

Tick-borne diseases (TBDs) constitute a significant concern worldwide, posing a threat to human and animal health alike. TBD spread is driven by various factors, including climatic and environmental changes, human behavioural and social factors, and different types of animal management practices. These factors support the circulation of both ticks and the pathogens they transmit.

While we know that the incidence of tick-borne diseases has been increasing in many regions, we do not know yet if this is the response to changes in the “rules of the game” (i.e., changes in tick abundance) or is just a result of greater TBD awareness.

Climate change, in particular, has been associated with the geographical expansion of ticks into new areas, increasing the risk of tick-borne diseases. However, we should not forget the importance of wild fauna, the natural hosts of ticks, in supporting these foci.

In recent years, significant research has been conducted on TBDs in animals. However, the continuous advance of science mandates that this knowledge continuously evolve. The causative agents, transmission patterns, and geographical distribution of these diseases have been extensively studied, with focus placed on the identification and ecology of tick species involved in transmission of pathogens to humans and/or animals.

Our aim in launching this Special Issue of Pathogens is to bring a spotlight more than the common tick-related topics published in the scientific literature. We propose that researchers focus on sets of important topics that leave an open door for multidisciplinary collaborations.

These contributions should be ideally focused on the following topics:

1. What species of Babesia circulates among pets in the northern hemisphere? What species of ticks is transmitting them? What is the level of evidence regarding the transmission?
   To note, in this epigraph, the focus is on “evidence”, as well as on an agenda for the future research needed in this field. Topics may cover concerns related to tick species expansion. For example, Dermacentor reticulatus in Europe seems to expand species range, but we need a clear explanation of the proposed reasons.
2. Which species of Theileria have been described so far (with real grounds) in ruminants and horses? Which species of ticks have been involved in the transmission? What is the real EVIDENCE supporting these arguments? This topic is NOT open to a long list of species, but to a coherent view of the complex relationships between ticks and protozoans. As before, we aim to increase the evidence of transmission and an agenda for research is also welcomed. A special focus on the omics relationships between Babesia and Theileria would be highly advantageous.
3. The economic burden of ticks and tick-borne pathogens on humans. We must determine a way to calculate the actual TBD-related costs in humans, including labour hours of health-care personnel and other persons involved in these disease management, days of hospitalization, costs of antibiotics? We must inquire: what do we need to evaluate all the above? Are there any cost-related studies available? How should all these incomes/outcomes be calculated? How much are the tick-borne pathogens-related costs and how do the affect the health system in each country? What are the estimated hours of labour lost? What are the estimated healthcare costs (antibiotics, health-care professionals, nurse salaries, etc.)? On the other hand, what would be the cost of the prevention programs, campaign, and an adequate protection? This topic is especially focused on human health specialists. However, the calculation of a similar approach for animals would be very much welcomed.
4. Tick-transmitted viruses. What is the burden of these viruses? How are the foci of these driven viruses? What is the contribution of the ticks and vertebrates (and other reservoirs)? How does the climate drive these foci? What phylogenetic relationships are behind the observed reports? Please note, the issue is NOT devoted to another list of species and/or vectors, and is NOT focused only on Flaviviridae. We are seeking to publish a generalepidemiology review, including tick vectors, reservoirs, and PROOFS of transmission.
5. Can we be confident with the so-called citizen science to map the tick distribution? Is it a clear contribution to make better maps of distribution? Are maps derived from these data biased? (Please provide with actual data). Is this contribution a simple set of data that does not improve our knowledge on tick distribution from field collections? Is such an effort necessary? We are in the age of "citizen science”. Does it really improve our knowledge of the tick distribution? How do researchers identify ticks using a poor picture captured by a cell phone of a red point over a hairy leg? What systems have been implemented in different countries? What are their pros and Cons? Is the perception of humans towards ticks changing over the last years?
6. The utilisation of tick vaccines for pets as a method to avoid the spread of ticks in urban habitats. Do we only possess knowledge thus far of chemicals in relation to this? (Only chemicals?) Are there REAL vaccine candidates, considering that pet owners want to see how the ticks drop off quickly? What are the pros and the cons of these vaccines? Are we nearing an optimistic future in which “ticks on pets” (and the derived issues on human heath) could be solved by a vaccine? What are the properties necessary for a vaccine to work?
7. The future of tick control on livestock. Are there any future perspectives other than the contaminating chemicals and the vaccines that never did work well in the field? What does a realistic view of the future look like? What do we need to do in order to improve animal production and well-being? Should vaccines be used and contaminating acaricides finally rejected?
8. Climate and ticks. Are we able to develop better models, accounting simultaneously for hosts and the competence phenomena among them? What is better, the “high resolution” or the “community view”? What other options are there, and what are their pros and cons? If we develop these models, what could be the expected usage and how should it be delivered to the final user?

Please feel free to share your topic proposals with the Editors that cover the chapters mentioned above, and we will gladly exchange points of view. Reviews articles should address the specific points mentioned above and focus on aspects of the field neglected in the past. We are excited to read your valuable contributions.

Dr. Gianluca D'Amico
Dr. Agustin Estrada Pena
Guest Editors

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